1. Field of the Invention
This invention relates to a surgical fastening apparatus, and more particularly to an apparatus for clamping tissue, especially vascular tissue, and subsequently driving an individual fastener through the tissue and into contact with the fastener anvil.
2. Description of the Related Art
Surgical apparatus for applying clips to vascular tissue are well known in the art. In these devices, each leg of the clip, typically U-shaped in configuration, is held in one of the opposing jaws of the instrument and the jaws are placed on sides of the vessel. The jaws are then closed to flatten the clip to squeeze the vessel walls together to effect hemostasis. These prior apparatus suffer from the disadvantage that the clip can only be advanced into the jaws of the instrument when the jaws are open so that vessel clamping and clip closing occur simultaneously. As a result, the surgeon cannot first ensure the vessel is properly clamped before committing to clip closure. Another disadvantage of these clip appliers is they can only be utilized to close a single vessel since they straddle the vessel; they cannot be used to attach approximated vessels or vessel portions.
A known method for repairing vascular tissue is suturing. Although two approximated vessels can be attached by this method, it is not only time consuming, but is difficult to accomplish in certain procedures, especially when the vessel is not in an easily accessible location. Still another disadvantage of suturing is that numerous punctures are made in the vessel walls since a hole is created with each passage of the suture needle.
Instruments for applying single staples one at a time to body tissue are also known. In contrast to clip appliers, these instruments include one jaw which contains a staple and an opposing jaw which has an anvil for deforming the legs of the staple. For example, U.S. Pat. No. 3,278,107 discloses a device where closing of the handles clamps the vessels and forms a single staple. This instrument suffers from the disadvantage associated with the above described clip appliers since clamping of the tissue and application of the staple occur simultaneously. U.S. Pat. No. 3,604,561 also discloses a stapler having a pair of clamping jaws and a mechanism for advancing the staple into an anvil. When sufficient force is applied to the handles, the staple is driven through the tissue and into the anvil. This instrument is deficient in that premature firing could occur if too much force is applied to the handles during the initial clamping action. Additionally, the surgeon cannot readily differentiate when the tissue clamping is completed and the staple firing stroke is initiated within sufficient time to unclamp the tissue. These prior art staplers suffer from the further disadvantage that they permit the handles to be opened and the instrument removed prior to complete staple formation. Thus, a partially formed staple can be left in the patient's body with potential tissue-damaging consequences.
The need therefore exists for an improved surgical fastener which can apply fasteners one at a time to body tissue such as vascular tissue and in which the user can unclamp and/or reposition the tissue in the engaging jaws before firing a fastener. The need also exists for an instrument which can indicate to the user when the tissue clamping action is complete and the fastener firing mechanism is about to be actuated. There is a further need for an instrument which, once fastener firing has begun, can be withdrawn by the user only after fastener formation is completed. Such an instrument could be utilized for closing individual vessels as well as attaching approximated vessels.